engleski

Characterization of wood surface degradation using FTIR, microtensile testing and colour measurements

Numerous studies of wood weathering phenomena led to good general knowledge regarding principle breakdown processes during exposures. However, results obtained using different methods are incoherent and dependent on the particularities of the testing method applied. In order to better understand the processes which happen on and under the wood surface during weathering as well as to identify the most influential wavebands of light causing photodegradation of wood, several weathering tests (artificial and natural) were performed. Batches of thin strips of fir wood, assembled in packs of matching three strips (thus forming a 240 m thick surface layer), were exposed to irradiation behind a set of cut-on glass filters that transmitted selected regions of the UV and visible spectrum in the range of wavelengths from 295 up to 515 nm. Weathering regimes included different light sources and various levels of climatic conditions (temperature and relative humidity of air). Discoloration developed disproportionally faster in early phases of exposure ; finite span microtensile strength reached saturation in the middle of the exposure period, whereas zero span strength and chemical changes reached their maxima at the end of exposures. This practically means that, different methods revealed different nature and extent of "damage" in specific phases of exposure and only the combination of results can give a complete image of the process.

wood, FTIR, colour, microtensile testing

nije evidentirano